Exhaust aftertreatment systems receive and treat exhaust generated from an internal combustion engine. Typical exhaust aftertreatment systems include any of various components configured to reduce the level of harmful exhaust emissions present in the exhaust. For example, some exhaust aftertreatment systems for diesel powered internal combustion engines include a particulate matter filter, a diesel oxidation catalyst, and a selective catalytic reduction (SCR) catalyst. Hot exhaust gas from the engine passes through each of the components before being expelled into the environment.
The exhaust aftertreatment components include a housing that defines an interior cavity in which an exhaust-treating filter or catalyst is housed. As the hot exhaust gas passes through the interior cavity, heat from the exhaust gas can increase the surface temperature of the walls of the housing. Due to potential safety hazards associated with excessive surface temperatures, safety regulations are in place to limit the maximum temperature of the external surfaces of the housings. In order to comply with the safety regulating, attempts have been made to reduce the external surface temperature of exhaust aftertreatment components. In one conventional exhaust aftertreatment system, a layer of insulation layer is wrapped over the external surface of the component housings.
In another conventional exhaust aftertreatment system, a layer of insulation is positioned within a space defined between an external wall and an internal wall of the component housings. This method is particularly useful where the external surface of the component is used for clamping the component to a vehicle and thus cannot be covered with insulation. The space is a fully enclosed compartment that is not directly exposed to the hot exhaust gas as it passes through the component. Further, the external and internal walls of the component housings are not configured to compress the insulation layer.